Atomic layer deposition systems and methods including metal beta-diketiminate compounds

ABSTRACT

The present invention provides atomic layer deposition systems and methods that include metal compounds with at least one β-diketiminate ligand. Such systems and methods can be useful for depositing metal-containing layers on substrates.

BACKGROUND

The scaling down of integrated circuit devices has created a need toincorporate high dielectric constant materials into capacitors andgates. The search for new high dielectric constant materials andprocesses is becoming more important as the minimum size for currenttechnology is practically constrained by the use of standard dielectricmaterials. Dielectric materials containing alkaline earth metals canprovide a significant advantage in capacitance compared to conventionaldielectric materials. For example, the perovskite material SrTiO₃ has areported bulk dielectric constant of up to 500.

Unfortunately, the successful integration of alkaline earth metals intovapor deposition processes has proven to be difficult. For example,although atomic layer deposition (ALD) of alkaline earth metaldiketonates has been reported, these metal diketonates have lowvolatility, which typically requires that they be dissolved in organicsolvent for use in a liquid injection system. In addition to lowvolatility, these metal diketonates generally have poor reactivity,often requiring high substrate temperatures and strong oxidizers to growa film, which is often contaminated with carbon. Other alkaline earthmetal sources, such as those including substituted or unsubstitutedcyclopentadienyl ligands, typically have poor volatility as well as lowthermal stability, leading to undesirable pyrolysis on the substratesurface.

New sources and methods of incorporating high dielectric materials arebeing sought for new generations of integrated circuit devices.

SUMMARY OF THE INVENTION

The present invention provides vapor deposition methods and systems thatinclude at least one compound of the formula (Formula I):

wherein M is selected from the group consisting of a Group 2 metal, aGroup 3 metal, a Lanthanide, and combinations thereof; each L isindependently an anionic ligand; each Y is independently a neutralligand; each R¹, R², R³, R⁴, and R⁵ is independently hydrogen or anorganic group; n represents the valence state of the metal; z is from 0to 10; and x is from 1 to n.

In one aspect, the present invention provides a method of forming ametal-containing layer on a substrate. The method includes: providing asubstrate; providing a vapor including at least one compound of theformula (Formula I):

wherein M, L, Y, R¹, R², R³, R⁴, R⁵, n, x, and z are as described hereinabove; providing at least one reaction gas; and contacting the vaporincluding the at least one compound of Formula I with the substrate toform a metal-containing layer on at least one surface of the substrateusing an atomic layer deposition process including a plurality ofdeposition cycles. Optionally, the method further includes providing avapor including at least one metal-containing compound different thanFormula I (e.g., Ti, Ta, Bi, Hf, Zr, Pb, Nb, Mg, and/or Al-containingcompounds), and contacting the vapor including the at least onemetal-containing compound different than Formula I with the substrate.

In another aspect, the present invention provides a method ofmanufacturing a semiconductor structure. The method includes: providinga semiconductor substrate or substrate assembly; providing a vaporincluding at least one compound of the formula (Formula I):

wherein M, L, Y, R¹, R², R³, R⁴, R⁵, n, x, and z are as described hereinabove; providing a vapor including at least one metal-containingcompound different than Formula I; and directing the vapor including theat least one compound of Formula I and the vapor including the at leastone metal-containing compound different than Formula I to thesemiconductor substrate or substrate assembly to form a metal-containinglayer on at least one surface of the semiconductor substrate orsubstrate assembly using an atomic layer deposition process including aplurality of deposition cycles. In some embodiments, during the atomiclayer deposition process, the metal-containing layer is formed byalternately introducing the vapor including the at least one compound ofFormula I and the vapor including the at least one metal-containingcompound different than Formula I during each deposition cycle.

In another aspect, the present invention provides a method ofmanufacturing a semiconductor structure. The method includes: providinga semiconductor substrate or substrate assembly within an atomic layerdeposition chamber; providing a vapor including at least one compound ofthe formula (Formula I):

wherein M, L, Y, R¹, R², R³, R⁴, R⁵, n, x, and z are as described hereinabove; providing a vapor including at least one metal-containingcompound different than Formula I; directing the vapor including the atleast one compound of Formula I to the semiconductor substrate orsubstrate assembly and allowing the at least one compound to chemisorbto at least one surface of the semiconductor substrate or substrateassembly; and directing the vapor including the at least onemetal-containing compound different than Formula I to the semiconductorsubstrate or substrate assembly and allowing the at least one compounddifferent than Formula I to chemisorb to at least one surface of thesemiconductor substrate or substrate assembly to form a metal-containinglayer on at least one surface of the semiconductor substrate orsubstrate assembly. In certain embodiments, directing the vaporincluding the at least one compound of Formula I to the semiconductorsubstrate or substrate assembly, and directing the vapor including theat least one metal-containing compound different than Formula I to thesemiconductor substrate or substrate assembly, are repeated at leastonce.

In another aspect, the present invention provides a method ofmanufacturing a memory device structure. The method includes: providinga substrate having a first electrode thereon; providing a vaporincluding at least one compound of the formula (Formula I):

wherein M, L, Y, R¹, R², R³, R⁴, R⁵, n, x, and z are as described hereinabove; contacting the vapor including the at least one compound ofFormula I with the substrate to chemisorb the compound on the firstelectrode of the substrate; providing at least one reaction gas;contacting the at least one reaction gas with the substrate having thechemisorbed compound thereon to form a dielectric layer on the firstelectrode of the substrate; and forming a second electrode on thedielectric layer.

In another aspect, the present invention provides an atomic layer vapordeposition system including: a deposition chamber having a substratepositioned therein; and at least one vessel including at least onecompound of the formula (Formula I):

wherein M, L, Y, R¹, R², R³, R⁴, R⁵, n, x, and z are as described hereinabove.

The metal-containing compounds that include β-diketiminate ligands canadvantageously be used in atomic layer deposition methods to deposit,for example, high dielectric films. In addition, ceramic coatings can bedeposited for use in ferroelectric, piezoelectric, and/or heat resistivecoating applications.

DEFINITIONS

As used herein, formulas of the type:

are used to represent pentadienyl-group type ligands (e.g.,β-diketiminate ligands) having delocalized electron density that arecoordinated to a metal. The ligands may be coordinated to the metalthrough one, two, three, four, and/or five atoms (i.e., η¹-, η²-, η³-,η⁴-, and/or η⁵-coordination modes).

As used herein, “a,” “an,” “the,” and “at least one” are usedinterchangeably and mean one or more than one.

The terms “deposition process” and “vapor deposition process” as usedherein refer to a process in which a metal-containing layer is formed onone or more surfaces of a substrate (e.g., a doped polysilicon wafer)from vaporized precursor composition(s) including one or moremetal-containing compounds(s). Specifically, one or moremetal-containing compounds are vaporized and directed to and/orcontacted with one or more surfaces of a substrate (e.g., semiconductorsubstrate or substrate assembly) placed in a deposition chamber.Typically, the substrate is heated. These metal-containing compoundsform (e.g., by reacting or decomposing) a non-volatile, thin, uniform,metal-containing layer on the surface(s) of the substrate. For thepurposes of this invention, the term “vapor deposition process” is meantto include both chemical vapor deposition processes (including pulsedchemical vapor deposition processes) and atomic layer depositionprocesses.

The term “atomic layer deposition” (ALD) as used herein refers to avapor deposition process in which deposition cycles, preferably aplurality of consecutive deposition cycles, are conducted in a processchamber (i.e., a deposition chamber). Typically, during each cycle theprecursor is chemisorbed to a deposition surface (e.g., a substrateassembly surface or a previously deposited underlying surface such asmaterial from a previous ALD cycle), forming a monolayer orsub-monolayer that does not readily react with additional precursor(i.e., a self-limiting reaction). Thereafter, if necessary, a reactant(e.g., another precursor or reaction gas) may subsequently be introducedinto the process chamber for use in converting the chemisorbed precursorto the desired material on the deposition surface. Typically, thisreactant is capable of further reaction with the precursor. Further,purging steps may also be utilized during each cycle to remove excessprecursor from the process chamber and/or remove excess reactant and/orreaction byproducts from the process chamber after conversion of thechemisorbed precursor. Further, the term “atomic layer deposition,” asused herein, is also meant to include processes designated by relatedterms such as, “chemical vapor atomic layer deposition”, “atomic layerepitaxy” (ALE) (see U.S. Pat. No. 5,256,244 to Ackerman), molecular beamepitaxy (MBE), gas source MBE, or organometallic MBE, and chemical beamepitaxy when performed with alternating pulses of precursorcomposition(s), reactive gas, and purge (e.g., inert carrier) gas.

As compared to the one cycle chemical vapor deposition (CVD) process,the longer duration multi-cycle ALD process allows for improved controlof layer thickness and composition by self-limiting layer growth, andminimizing detrimental gas phase reactions by separation of the reactioncomponents. The self-limiting nature of ALD provides a method ofdepositing a film on any suitable reactive surface, including surfaceswith irregular topographies, with better step coverage than is availablewith CVD or other “line of sight” deposition methods such as evaporationor physical vapor deposition (PVD or sputtering).

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a perspective view of a vapor deposition system suitable foruse in methods of the present invention.

FIG. 2 is an exemplary capacitor construction formed using systems andmethods of the present invention.

DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS

The present invention provides methods and systems for forming ametal-containing layer on a substrate using atomic layer deposition. Themethods include providing a vapor of at least one metal-containingcompound that includes at least one β-diketiminate ligand. In someembodiments, the metal compounds are homoleptic complexes (i.e.,complexes in which the metal is bound to only one type of ligand) thatinclude β-diketiminate ligands, which can be symmetric or unsymmetric.In other embodiments, the metal compounds are heteroleptic complexes(i.e., complexes in which the metal is bound to more than one type ofligand) including at least one β-diketiminate ligand, which can besymmetric or unsymmetric. In some embodiments, the β-diketiminate ligandcan be in the η⁵-coordination mode.

Suitable metal-containing compounds that include one or moreβ-diketiminate ligands include compounds of the formula (Formula I):

M is a Group 2 metal (e.g., Ca, Sr, Ba), a Group 3 metal (e.g., Sc, Y,La), a Lanthanide (e.g., Pr, Nd), or a combination thereof. Preferably Mis Ca, Sr, or Ba. Each L is independently an anionic ligand; each Y isindependently a neutral ligand; n represents the valence state of themetal; z is from 0 to 10; and x is from 1 to n.

Each R¹, R², R³, R⁴, and R⁵ is independently hydrogen or an organicgroup (e.g., an alkyl group, and preferably, for example, an alkylmoiety). In certain embodiments, each R¹, R², R³, R⁴, and R⁵ isindependently hydrogen or an organic group having 1-10 carbon atoms(e.g., methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, tert-butyl).Such compounds include, for example, those described in El-Kaderi etal., Organometallics, 23:4995-5002 (2004), and copending U.S.application Ser. No. ______ (entitled “UNSYMMETRICAL LIGAND SOURCES,REDUCED SYMMETRY METAL COMPOUNDS, AND SYSTEMS AND METHODS INCLUDINGSAME,” Attorney Docket No. 150.01460101), filed on the same dayherewith.

In certain embodiments, the β-diketiminate ligand shown in Formula I issymmetric (i.e., R¹=R⁵, and R²=R⁴). In some embodiments, R²=R⁴=methyl.In some embodiments, R³=H. In some embodiments, R¹=R⁵=isopropyl. In someembodiments, R¹=R⁵=tert-butyl. Such exemplary compounds of Formula Iinclude a compound in which R²=R⁴=methyl, R³=H, and R¹=R⁵=isopropyl; anda compound in which R²=R⁴=methyl, R³=H, and R¹=R⁵=tert-butyl.

In other certain embodiments, the β-diketiminate ligand shown in FormulaI is unsymmetric (i.e., one or more of the following apply: R¹ isdifferent than R⁵, or R² is different than R⁴). In some embodiments.R²=R⁴=methyl. In some embodiments. R³=H. In some embodiments,R¹=isopropyl and R⁵=tert-butyl. Such exemplary compounds of Formula Iare compounds in which R²=R⁴=methyl, R³=H, R¹=isopropyl, andR⁵=tert-butyl.

L optionally represents any suitable anionic ligand. Exemplary anionicligands (L) include halides, alkoxide groups, amide groups, mercaptidegroups, cyanide, alkyl groups, amidinate groups, guanidinate groups,isoureate groups, β-diketonate groups, β-iminoketonate groups,β-diketiminate groups, and combinations thereof. In certain embodiments.L is a β-diketiminate group having a structure that is the same as thatof the β-diketiminate ligand shown in Formula I. In other certainembodiments, L is a β-diketiminate group (e.g., symmetric orunsymmetric) having a structure that is different than that of theβ-diketiminate ligand shown in Formula I.

Y represents an optional neutral ligand. Exemplary neutral ligands (Y)include carbonyl (CO), nitrosyl (NO), ammonia (NH₃), amines (NR₃),nitrogen (N₂), phosphines (PR₃), alcohols (ROH), water (H₂O),tetrahydrofuran, and combinations thereof, wherein each R independentlyrepresents hydrogen or an organic group. The number of optional neutralligands (Y) is represented by z, which is from 0 to 10, and preferablyfrom 0 to 3. More preferably, Y is not present (i.e., z=0).

As used herein, the term “organic group” is used for the purpose of thisinvention to mean a hydrocarbon group that is classified as an aliphaticgroup, cyclic group, or combination of aliphatic and cyclic groups(e.g., alkaryl and aralkyl groups). In the context of the presentinvention, suitable organic groups for metal-containing compounds ofthis invention are those that do not interfere with the formation of ametal oxide layer using vapor deposition techniques. In the context ofthe present invention, the term “aliphatic group” means a saturated orunsaturated linear or branched hydrocarbon group. This term is used toencompass alkyl, alkenyl, and alkynyl groups, for example. The term“alkyl group” means a saturated linear or branched monovalenthydrocarbon group including, for example, methyl, ethyl, n-propyl,isopropyl, t-butyl, amyl, heptyl, and the like. The term “alkenyl group”means an unsaturated, linear or branched monovalent hydrocarbon groupwith one or more olefinically unsaturated groups i.e., carbon-carbondouble bonds), such as a vinyl group. The term “alkynyl group” means anunsaturated, linear or branched monovalent hydrocarbon group with one ormore carbon-carbon triple bonds. The term “cyclic group” means a closedring hydrocarbon group that is classified as an alicyclic group,aromatic group, or heterocyclic group. The term “alicyclic group” meansa cyclic hydrocarbon group having properties resembling those ofaliphatic groups. The term “aromatic group” or “aryl group” means amono- or polynuclear aromatic hydrocarbon group. The term “heterocyclicgroup” means a closed ring hydrocarbon in which one or more of the atomsin the ring is an element other than carbon (e.g., nitrogen, oxygen,sulfur, etc.).

As a means of simplifying the discussion and the recitation of certainterminology used throughout this application, the terms “group” and“moiety” are used to differentiate between chemical species that allowfor substitution or that may be substituted and those that do not soallow for substitution or may not be so substituted. Thus, when the term“group” is used to describe a chemical substituent, the describedchemical material includes the unsubstituted group and that group withnonperoxidic O, N, S, Si, or F atoms, for example, in the chain as wellas carbonyl groups or other conventional substituents. Where the term“moiety” is used to describe a chemical compound or substituent, only anunsubstituted chemical material is intended to be included. For example,the phrase “alkyl group” is intended to include not only pure open chainsaturated hydrocarbon alkyl substituents, such as methyl, ethyl, propyl,t-butyl, and the like, but also alkyl substituents bearing furthersubstituents known in the art, such as hydroxy, alkoxy, alkylsulfonyl,halogen atoms, cyano, nitro, amino, carboxyl, etc. Thus, “alkyl group”includes ether groups, haloalkyls, nitroalkyls, carboxyalkyls,hydroxyalkyls, sulfoalkyls, etc. On the other hand, the phrase “alkylmoiety” is limited to the inclusion of only pure open chain saturatedhydrocarbon alkyl substituents, such as methyl, ethyl, propyl, t-butyl,and the like.

Precursor compositions that include a metal-containing compound with atleast one β-diketiminate ligand can be useful for depositingmetal-containing layers using atomic layer deposition. In addition, suchatomic layer deposition methods can also include precursor compositionsthat include one or more different metal-containing compounds. Suchprecursor compositions can be deposited/chemisorbed, for example in anALD process discussed more fully below, substantially simultaneouslywith or sequentially to, the precursor compositions includingmetal-containing compounds with at least one β-diketiminate ligand. Themetals of such different metal-containing compounds can include, forexample, Ti, Ta, Bi, Hf, Zr, Pb, Nb, Mg, Al, and combinations thereof.Suitable different metal-containing compounds include, for example,tetrakis titanium isopropoxide, titanium tetrachloride,trichlorotitanium dialkylamides, tetrakis titanium dialkylamides,tetrakis hafnium dialkylamides, trimethyl aluminum, zirconium (IV)chloride, pentakis tantalum ethoxide, and combinations thereof.

The metal-containing layer can be deposited, for example, on a substrate(e.g., a semiconductor substrate or substrate assembly). The terms“substrate,” “semiconductor substrate,” or “substrate assembly” as usedherein refer to either a substrate or a semiconductor substrate, such asa base semiconductor layer or a semiconductor substrate having one ormore layers, structures, or regions formed thereon. A base semiconductorlayer is typically the lowest layer of silicon material on a wafer or asilicon layer deposited on another material, such as silicon onsapphire. When reference is made to a substrate assembly, variousprocess steps may have been previously used to form or define regions,junctions, various structures or features, and openings such astransistors, active areas, diffusions, implanted regions, vias, contactopenings, high aspect ratio openings, capacitor plates, barriers forcapacitors, etc.

“Layer,” as used herein, refers to any layer that can be formed on asubstrate from one or more precursors and/or reactants according to thedeposition process described herein. The term “layer” is meant toinclude layers specific to the semiconductor industry, such as, butclearly not limited to, a barrier layer, dielectric layer (i.e., a layerhaving a high dielectric constant), and conductive layer. The term“layer” is synonymous with the term “film” frequently used in thesemiconductor industry. The term “layer” is also meant to include layersfound in technology outside of semiconductor technology, such ascoatings on glass. For example, such layers can be formed directly onfibers, wires, etc., which are substrates other than semiconductorsubstrates. Further, the layers can be formed directly on the lowestsemiconductor surface of the substrate, or they can be formed on any ofa variety of layers (e.g., surfaces) as in, for example, a patternedwafer.

The layers or films formed may be in the form of metal-containing films,such as reduced metals, metal silicates, metal oxides, metal nitrides,etc, as well as combinations thereof. For example, a metal oxide layermay include a single metal, the metal oxide layer may include two ormore different metals (i.e., it is a mixed metal oxide), or a metaloxide layer may optionally be doped with other metals.

If the metal oxide layer includes two or more different metals, themetal oxide layer can be in the form of alloys, solid solutions, ornanolaminates. Preferably, these have dielectric properties. The metaloxide layer (particularly if it is a dielectric layer) preferablyincludes one or more of BaTiO₃, SrTiO₃, CaTiO₃, (Ba,Sr)TiO₃, SrTa₂O₆,SrBi₂Ta₂O₉ (SBT), SrHfO₃, SrZrO₃, BaHfO₃, BaZrO₃, (Pb,Ba)Nb₂O₆,(Sr,Ba)Nb₂O₆, Pb[(Sc,Nb)_(0.575)Ti_(0.425)]O₃ (PSNT), La₂O₃, Y₂O₃,LaAlO₃, YAlO₃, Pr₂O₃, Ba(Li,Nb)_(1/4)O₃—PbTiO₃, andBa(0.6)Sr(0.4)TiO₃—MgO. Surprisingly, the metal oxide layer formedaccording to the present invention is essentially free of carbon.Preferably metal-oxide layers formed by the systems and methods of thepresent invention are essentially free of carbon, hydrogen, halides,phosphorus, sulfur, nitrogen or compounds thereof. As used herein,“essentially free” is defined to mean that the metal-containing layermay include a small amount of the above impurities. For example, formetal-oxide layers, “essentially free” means that the above impuritiesare present in an amount of less than 1 atomic percent, such that theyhave a minor effect on the chemical properties, mechanical properties,physical form (e.g., crystallinity), or electrical properties of thefilm.

Various metal-containing compounds can be used in various combinations,optionally with one or more organic solvents (particularly for CVDprocesses), to form a precursor composition. Advantageously, some of themetal compounds disclosed herein can be used in ALD without addingsolvents. “Precursor” and “precursor composition” as used herein, referto a composition usable for forming, either alone or with otherprecursor compositions (or reactants), a layer on a substrate assemblyin a deposition process. Further, one skilled in the art will recognizethat the type and amount of precursor used will depend on the content ofa layer which is ultimately to be formed using a vapor depositionprocess. The preferred precursor compositions of the present inventionare preferably liquid at the vaporization temperature and, morepreferably, are preferably liquid at room temperature.

The precursor compositions may be liquids or solids at room temperature(preferably, they are liquids at the vaporization temperature).Typically, they are liquids sufficiently volatile to be employed usingknown vapor deposition techniques. However, as solids they may also besufficiently volatile that they can be vaporized or sublimed from thesolid state using known vapor deposition techniques. If they are lessvolatile solids, they are preferably sufficiently soluble in an organicsolvent or have melting points below their decomposition temperaturessuch that they can be used in flash vaporization, bubbling, microdropletformation techniques, etc.

Herein, vaporized metal-containing compounds may be used either alone oroptionally with vaporized molecules of other metal-containing compoundsor optionally with vaporized solvent molecules or inert gas molecules,if used. As used herein, “liquid” refers to a solution or a neat liquid(a liquid at room temperature or a solid at room temperature that meltsat an elevated temperature). As used herein, “solution” does not requirecomplete solubility of the solid but may allow for some undissolvedsolid, as long as there is a sufficient amount of the solid delivered bythe organic solvent into the vapor phase for chemical vapor depositionprocessing. If solvent dilution is used in deposition, the total molarconcentration of solvent vapor generated may also be considered as ainert carrier gas.

“Inert gas” or “non-reactive gas,” as used herein, is any gas that isgenerally unreactive with the components it comes in contact with. Forexample, inert gases are typically selected from a group includingnitrogen, argon, helium, neon, krypton, xenon, any other non-reactivegas, and mixtures thereof. Such inert gases are generally used in one ormore purging processes described according to the present invention, andin some embodiments may also be used to assist in precursor vaportransport.

Solvents that are suitable for certain embodiments of the presentinvention may be one or more of the following: aliphatic hydrocarbons orunsaturated hydrocarbons (C3-C20, and preferably C5-C10, cyclic,branched, or linear), aromatic hydrocarbons (C5-C20, and preferablyC5-C10), halogenated hydrocarbons, silylated hydrocarbons such asalkylsilanes, alkylsilicates, ethers, polyethers, thioethers, esters,lactones, nitriles, silicone oils, or compounds containing combinationsof any of the above or mixtures of one or more of the above. Thecompounds are also generally compatible with each other, so thatmixtures of variable quantities of the metal-containing compounds willnot interact to significantly change their physical properties.

The precursor compositions of the present invention can, optionally, bevaporized and deposited chemisorbed substantially simultaneously with,and in the presence of, one or more reaction gases. Alternatively, themetal-containing layers may be formed by alternately introducing theprecursor composition and the reaction gas(es) during each depositioncycle. Such reaction gases may typically include oxygen, water vapor,ozone, nitrogen oxides, sulfur oxides, hydrogen, hydrogen sulfide,hydrogen selenide, hydrogen telluride, hydrogen peroxide, ammonia,organic amines, hydrazines (e.g., hydrazine, methylhydrazine,symmetrical and unsymmetrical dimethylhydrazines), silanes, disilanesand higher silanes, diborane, plasma, air, borazene (nitrogen source),carbon monoxide (reductant), alcohols, and any combination of thesegases. For example, oxygen-containing sources are typically used for thedeposition of metal-oxide layers. Preferable optional reaction gasesused in the formation of metal-oxide layers include oxidizing gases(e.g., oxygen, ozone, and nitric oxide).

Suitable substrate materials of the present invention include conductivematerials, semiconductive materials, conductive metal-nitrides,conductive metals, conductive metal oxides, etc. The substrate on whichthe metal-containing layer is formed is preferably a semiconductorsubstrate or substrate assembly. Any suitable semiconductor material iscontemplated, such as for example, borophosphosilicate glass (BPSG),silicon such as, e.g., conductively doped polysilicon, monocrystallinesilicon, etc. (for this invention, appropriate forms of silicon aresimply referred to as “silicon”), for example in the form of a siliconwafer, tetraethylorthosilicate (TEOS) oxide, spin on glass (i.e., a thinlayer of SiO₂, optionally doped, deposited by a spin on process), TiN,TaN, W, Ru, Al, Cu, noble metals, etc. A substrate assembly may alsocontain a layer that includes platinum, iridium, iridium oxide, rhodium,ruthenium, ruthenium oxide, strontium ruthenate, lanthanum nickelate,titanium nitride, tantalum nitride, tantalum-silicon-nitride, silicondioxide, aluminum, gallium arsenide, glass, etc., and other existing orto-be-developed materials used in semiconductor constructions, such asdynamic random access memory (DRAM) devices, static random access memory(SRAM) devices, and ferroelectric memory (FERAM) devices, for example.

For substrates including semiconductor substrates or substrateassemblies, the layers can be formed directly on the lowestsemiconductor surface of the substrate, or they can be formed on any ofa variety of the layers (i.e., surfaces) as in a patterned wafer, forexample.

Substrates other than semiconductor substrates or substrate assembliescan also be used in methods of the present invention. Any substrate thatmay advantageously form a metal-containing layer thereon, such as ametal oxide layer, may be used, such substrates including, for example,fibers, wires, etc.

The precursor compositions can be vaporized in the presence of an inertcarrier gas if desired. Additionally, an inert carrier gas can be usedin purging steps in an ALD process (discussed below). The inert carriergas is typically one or more of nitrogen, helium, argon, etc. In thecontext of the present invention, an inert carrier gas is one that doesnot interfere with the formation of the metal-containing layer. Whetherdone in the presence of a inert carrier gas or not, the vaporization ispreferably done in the absence of oxygen to avoid oxygen contaminationof the layer (e.g., oxidation of silicon to form silicon dioxide oroxidation of precursor in the vapor phase prior to entry into thedeposition chamber).

Chemical vapor deposition (CVD) and atomic layer deposition (ALD) aretwo vapor deposition processes often employed to form thin, continuous,uniform, metal-containing layers onto semiconductor substrates. Usingeither vapor deposition process, typically one or more precursorcompositions are vaporized in a deposition chamber and optionallycombined with one or more reaction gases and directed to and/orcontacted with the substrate to form a metal-containing layer on thesubstrate. It will be readily apparent to one skilled in the art thatthe vapor deposition process may be enhanced by employing variousrelated techniques such as plasma assistance, photo assistance, laserassistance, as well as other techniques.

A typical CVD process may be carried out in a chemical vapor depositionreactor, such as a deposition chamber available under the tradedesignation of 7000 from Genus, Inc. (Sunnyvale, Calif.), a depositionchamber available under the trade designation of 5000 from AppliedMaterials, Inc. (Santa Clara, Calif.), or a deposition chamber availableunder the trade designation of Prism from Novelus, Inc. (San Jose,Calif.). However, any deposition chamber suitable for performing CVD maybe used.

Preferably, the vapor deposition process employed in the methods of thepresent invention is a multi-cycle atomic layer deposition (ALD)process. Such a process is advantageous, in particular advantageous overa CVD process, in that it provides for improved control of atomic-levelthickness and uniformity to the deposited layer (e.g., dielectric layer)by providing a plurality of self-limiting deposition cycles. Theself-limiting nature of ALD provides a method of depositing a film onany suitable reactive surface including, for example, surfaces withirregular topographies, with better step coverage than is available withCVD or other “line of sight” deposition methods (e.g., evaporation andphysical vapor deposition, i.e., PVD or sputtering). Further, ALDprocesses typically expose the metal-containing compounds to lowervolatilization and reaction temperatures, which tends to decreasedegradation of the precursor as compared to, for example, typical CVDprocesses.

Generally, in an ALD process each reactant is pulsed sequentially onto asuitable substrate, typically at deposition temperatures of at least 25°C., preferably at least 150° C., and more preferably at least 200° C.Typical ALD deposition temperatures are no greater than 400° C.,preferably no greater than 350° C., and even more preferably no greaterthan 250° C. These temperatures are generally lower than those presentlyused in CVD processes, which typically include deposition temperaturesat the substrate surface of at least 150° C., preferably at least 200°C., and more preferably at least 250° C. Typical CVD depositiontemperatures are no greater than 600° C., preferably no greater than500° C., and even more preferably no greater than 400° C.

Under such conditions the film growth by ALD is typically self-limiting(i.e., when the reactive sites on a surface are used up in an ALDprocess, the deposition generally stops), insuring not only excellentconformality but also good large area uniformity plus simple andaccurate composition and thickness control. Due to alternate dosing ofthe precursor compositions and/or reaction gases, detrimentalvapor-phase reactions are inherently eliminated, in contrast to the CVDprocess that is carried out by continuous co-reaction of the precursorsand/or reaction gases. (See Vehkamäki et al, “Growth of SrTiO₃ andBaTiO₃ Thin Films by Atomic Layer Deposition,” Electrochemical andSolid-State Letters, 2(10):504-506 (1999)).

A typical ALD process includes exposing a substrate (which mayoptionally be pretreated with, for example, water and/or ozone) to afirst chemical to accomplish chemisorption of the species onto thesubstrate. The term “chemisorption” as used herein refers to thechemical adsorption of vaporized reactive metal-containing compounds onthe surface of a substrate. The adsorbed species are typicallyirreversibly bound to the substrate surface as a result of relativelystrong binding forces characterized by high adsorption energies(e.g., >30 kcal/mol), comparable in strength to ordinary chemical bonds.The chemisorbed species typically form a monolayer on the substratesurface. (See “The Condensed Chemical Dictionary”, 10th edition, revisedby G. G. Hawley, published by Van Nostrand Reinhold Co., New York, 225(1981)). The technique of ALD is based on the principle of the formationof a saturated monolayer of reactive precursor molecules bychemisorption. In ALD one or more appropriate precursor compositions orreaction gases are alternately introduced (e.g., pulsed) into adeposition chamber and chemisorbed onto the surfaces of a substrate.Each sequential introduction of a reactive compound (e.g., one or moreprecursor compositions and one or more reaction gases) is typicallyseparated by an inert carrier gas purge. Each precursor compositionco-reaction adds a new atomic layer to previously deposited layers toform a cumulative solid layer. The cycle is repeated to gradually formthe desired layer thickness. It should be understood that ALD canalternately utilize one precursor composition, which is chemisorbed, andone reaction gas, which reacts with the chemisorbed species.

Practically, chemisorption might not occur on all portions of thedeposition surface (e.g., previously deposited ALD material).Nevertheless, such imperfect monolayer is still considered a monolayerin the context of the present invention. In many applications, merely asubstantially saturated monolayer may be suitable. In one aspect, asubstantially saturated monolayer is one that will still yield adeposited monolayer or less of material exhibiting the desired qualityand/or properties. In another aspect, a substantially saturatedmonolayer is one that is self-limited to further reaction withprecursor.

A typical ALD process includes exposing an initial substrate to a firstchemical species A (e.g., a metal-containing compound as describedherein) to accomplish chemisorption of the species onto the substrate.Species A can react either with the substrate surface or with Species B(described below), but not with itself. Typically in chemisorption, oneor more of the ligands of Species A is displaced by reactive groups onthe substrate surface. Theoretically, the chemisorption forms amonolayer that is uniformly one atom or molecule thick on the entireexposed initial substrate, the monolayer being composed of Species A,less any displaced ligands. In other words, a saturated monolayer issubstantially formed on the substrate surface. Practically,chemisorption may not occur on all portions of the substrate.Nevertheless, such a partial monolayer is still understood to be amonolayer in the context of the present invention. In many applications,merely a substantially saturated monolayer may be suitable. Asubstantially saturated monolayer is one that will still yield adeposited layer exhibiting the quality and/or properties desired forsuch layer.

The first species (e.g., substantially all non-chemisorbed molecules ofSpecies A) as well as displaced ligands are purged from over thesubstrate and a second chemical species, Species B (e.g., a differentmetal-containing compound or reactant gas) is provided to react with themonolayer of Species A. Species B typically displaces the remainingligands from the Species A monolayer and thereby is chemisorbed andforms a second monolayer. This second monolayer displays a surface whichis reactive only to Species A. Non-chemisorbed Species B, as well asdisplaced ligands and other byproducts of the reaction are then purgedand the steps are repeated with exposure of the Species B monolayer tovaporized Species A. Optionally, the second species can react with thefirst species, but not chemisorb additional material thereto. That is,the second species can cleave some portion of the chemisorbed firstspecies, altering such monolayer without forming another monolayerthereon, but leaving reactive sites available for formation ofsubsequent monolayers. In other ALD processes, a third species or moremay be successively chemisorbed (or reacted) and purged just asdescribed for the first and second species, with the understanding thateach introduced species reacts with the monolayer produced immediatelyprior to its introduction. Optionally, the second species (or third orsubsequent) can include at least one reaction gas if desired.

Thus, the use of ALD provides the ability to improve the control ofthickness, composition, and uniformity of metal-containing layers on asubstrate. For example, depositing thin layers of metal-containingcompound in a plurality of cycles provides a more accurate control ofultimate film thickness. This is particularly advantageous when theprecursor composition is directed to the substrate and allowed tochemisorb thereon, preferably further including at least one reactiongas that reacts with the chemisorbed species on the substrate, and evenmore preferably wherein this cycle is repeated at least once.

Purging of excess vapor of each species followingdeposition/chemisorption onto a substrate may involve a variety oftechniques including, but not limited to, contacting the substrateand/or monolayer with an inert carrier gas and/or lowering pressure tobelow the deposition pressure to reduce the concentration of a speciescontacting the substrate and/or chemisorbed species. Examples of carriergases, as discussed above, may include N₂, Ar, He, etc. Additionally,purging may instead include contacting the substrate and/or monolayerwith any substance that allows chemisorption by-products to desorb andreduces the concentration of a contacting species preparatory tointroducing another species. The contacting species may be reduced tosome suitable concentration or partial pressure known to those skilledin the art based on the specifications for the product of a particulardeposition process.

ALD is often described as a self-limiting process, in that a finitenumber of sites exist on a substrate to which the first species may formchemical bonds. The second species might only react with the surfacecreated from the chemisorption of the first species and thus, may alsobe self-limiting. Once all of the finite number of sites on a substrateare bonded with a first species, the first species will not bond toother of the first species already bonded with the substrate. However,process conditions can be varied in ALD to promote such bonding andrender ALD not self-limiting, e.g., more like pulsed CVD. Accordingly,ALD may also encompass a species forming other than one monolayer at atime by stacking of a species, forming a layer more than one atom ormolecule thick.

The described method indicates the “substantial absence” of the secondprecursor (i.e., second species) during chemisorption of the firstprecursor since insignificant amounts of the second precursor might bepresent. According to the knowledge and the preferences of those withordinary skill in the art, a determination can be made as to thetolerable amount of second precursor and process conditions selected toachieve the substantial absence of the second precursor.

Thus, during the ALD process, numerous consecutive deposition cycles areconducted in the deposition chamber, each cycle depositing a very thinmetal-containing layer (usually less than one monolayer such that thegrowth rate on average is 0.2 to 3.0 Angstroms per cycle), until a layerof the desired thickness is built up on the substrate of interest. Thelayer deposition is accomplished by alternately introducing (i.e., bypulsing) precursor composition(s) into the deposition chamber containinga substrate, chemisorbing the precursor composition(s) as a monolayeronto the substrate surfaces, purging the deposition chamber, thenintroducing to the chemisorbed precursor composition(s) reaction gasesand/or other precursor composition(s) in a plurality of depositioncycles until the desired thickness of the metal-containing layer isachieved. Preferred thicknesses of the metal-containing layers of thepresent invention are at least 1 angstrom (Å), more preferably at least5 Å, and more preferably at least 10 Å. Additionally, preferred filmthicknesses are typically no greater than 500 Å, more preferably nogreater than 400 Å, and more preferably no greater than 300 Å.

The pulse duration of precursor composition(s) and inert carrier gas(es)is generally of a duration sufficient to saturate the substrate surface.Typically, the pulse duration is at least 0.1, preferably at least 0.2second, and more preferably at least 0.5 second. Preferred pulsedurations are generally no greater than 5 seconds, and preferably nogreater than 3 seconds.

In comparison to the predominantly thermally driven CVD, ALD ispredominantly chemically driven. Thus, ALD may advantageously beconducted at much lower temperatures than CVD. During the ALD process,the substrate temperature may be maintained at a temperaturesufficiently low to maintain intact bonds between the chemisorbedprecursor composition(s) and the underlying substrate surface and toprevent decomposition of the precursor composition(s). The temperature,on the other hand, must be sufficiently high to avoid condensation ofthe precursor composition(s). Typically the substrate is kept at atemperature of at least 25° C., preferably at least 150° C., and morepreferably at least 200° C. Typically the substrate is kept at atemperature of no greater than 400° C., preferably no greater than 300°C., and more preferably no greater than 250° C., which, as discussedabove, is generally lower than temperatures presently used in typicalCVD processes. Thus, the first species or precursor composition ischemisorbed at this temperature. Surface reaction of the second speciesor precursor composition can occur at substantially the same temperatureas chemisorption of the first precursor or, optionally but lesspreferably, at a substantially different temperature. Clearly, somesmall variation in temperature, as judged by those of ordinary skill,can occur but still be considered substantially the same temperature byproviding a reaction rate statistically the same as would occur at thetemperature of the first precursor chemisorption. Alternatively,chemisorption and subsequent reactions could instead occur atsubstantially exactly the same temperature.

For a typical vapor deposition process, the pressure inside thedeposition chamber is at least 10⁻⁸ torr (1.3×10⁻⁶ Pa), preferably atleast 10⁻⁷ torr (1.3×10⁻⁵ Pa), and more preferably at least 10⁻⁶ torr(1.3×10⁻⁴ Pa). Further, deposition pressures are typically no greaterthan 10 torr (1.3×10³ Pa), preferably no greater than 1 torr (1.3×10²Pa), and more preferably no greater than 10⁻¹ torr (13 Pa). Typically,the deposition chamber is purged with an inert carrier gas after thevaporized precursor composition(s) have been introduced into the chamberand/or reacted for each cycle. The inert carrier gas/gases can also beintroduced with the vaporized precursor composition(s) during eachcycle.

The reactivity of a precursor composition can significantly influencethe process parameters in ALD. Under typical CVD process conditions, ahighly reactive compound may react in the gas phase generatingparticulates, depositing prematurely on undesired surfaces, producingpoor films, and/or yielding poor step coverage or otherwise yieldingnon-uniform deposition. For at least such reason, a highly reactivecompound might be considered not suitable for CVD. However, somecompounds not suitable for CVD are superior ALD precursors. For example,if the first precursor is gas phase reactive with the second precursor,such a combination of compounds might not be suitable for CVD, althoughthey could be used in ALD. In the CVD context, concern might also existregarding sticking coefficients and surface mobility, as known to thoseskilled in the art, when using highly gas-phase reactive precursors,however, little or no such concern would exist in the ALD context.

After layer formation on the substrate, an annealing process may beoptionally performed in situ in the deposition chamber in a reducing,inert, plasma, or oxidizing atmosphere. Preferably, the annealingtemperature is at least 400° C., more preferably at least 600° C. Theannealing temperature is preferably no greater than 1000° C., morepreferably no greater than 750° C., and even more preferably no greaterthan 700° C.

The annealing operation is preferably performed for a time period of atleast 0.5 minute, more preferably for a time period of at least 1minute. Additionally, the annealing operation is preferably performedfor a time period of no greater than 60 minutes, and more preferably fora time period of no greater than 10 minutes.

One skilled in the art will recognize that such temperatures and timeperiods may vary. For example, furnace anneals and rapid thermalannealing may be used, and further, such anneals may be performed in oneor more annealing steps.

As stated above, the use of the compounds and methods of forming filmsof the present invention are beneficial for a wide variety of thin filmapplications in semiconductor structures, particularly those using highdielectric materials. For example, such applications include gatedielectrics and capacitors such as planar cells, trench cells (e.g.double sidewall trench capacitors), stacked cells (e.g., crown, V-cell,delta cell, multi-fingered, or cylindrical container stackedcapacitors), as well as field effect transistor devices.

A system that can be used to perform an atomic layer depositionprocesses of the present invention is shown in FIG. 1. The systemincludes an enclosed vapor deposition chamber 10, in which a vacuum maybe created using turbo pump 12 and backing pump 14. One or moresubstrates 16 (e.g., semiconductor substrates or substrate assemblies)are positioned in chamber 10. A constant nominal temperature isestablished for substrate 16, which can vary depending on the processused. Substrate 16 may be heated, for example, by an electricalresistance heater 18 on which substrate 16 is mounted. Other knownmethods of heating the substrate may also be utilized.

In this process, precursor composition(s) as described herein, 60 and/or61, are stored in vessels 62. The precursor composition(s) are vaporizedand separately fed along lines 64 and 66 to the deposition chamber 10using, for example, an inert carrier gas 68. A reaction gas 70 may besupplied along line 72 as needed. Also, a purge gas 74, which is oftenthe same as the inert carrier gas 68, may be supplied along line 76 asneeded. As shown, a series of valves 80-85 are opened and closed asrequired.

FIG. 2 shows an example of the ALD formation of metal-containing layersof the present invention as used in an exemplary capacitor construction.Referring to FIG. 2, capacitor construction 200 includes substrate 210having conductive diffusion area 215 formed therein. Substrate 210 caninclude, for example, silicon. An insulating layer 260, such as BPSG, isprovided over substrate 210, with contact opening 280 provided thereinto diffusion area 215. Conductive material 290 fills contact opening280, and may include, for example, tungsten or conductively dopedpolysilicon. Capacitor construction 200 includes a first capacitorelectrode (a bottom electrode) 220, a dielectric layer 240 which may beformed by methods of the present invention, and a second capacitorelectrode (a top electrode) 250.

It is to be understood that FIG. 2 is an exemplary construction, andmethods of the invention can be useful for forming layers on anysubstrate, preferably on semiconductor structures, and that suchapplications include capacitors such as planar cells, trench cells,(e.g., double sidewall trench capacitors), stacked cells (e.g., crown,V-cell, delta cell, multi-fingered, or cylindrical container stackedcapacitors), as well as field effect transistor devices.

Furthermore, a diffusion barrier layer may optionally be formed over thedielectric layer 240, and may, for example, include TiN, TaN, metalsilicide, or metal silicide-nitride. While the diffusion barrier layeris described as a distinct layer, it is to be understood that thebarrier layers may include conductive materials and can accordingly, insuch embodiments, be understood to include at least a portion of thecapacitor electrodes. In certain embodiments that include a diffusionbarrier layer, an entirety of a capacitor electrode can includeconductive barrier layer materials.

The following examples are offered to further illustrate variousspecific embodiments and techniques of the present invention. It shouldbe understood, however, that many variations and modificationsunderstood by those of ordinary skill in the art may be made whileremaining within the scope of the present invention. Therefore, thescope of the invention is not intended to be limited by the followingexample. Unless specified otherwise, all percentages shown in theexamples are percentages by weight.

EXAMPLES Example 1 Atomic Layer Deposition of a Metal-ContainingCompound of Formula I (M=Sr (n=2); R¹=R⁵=tert-butyl; R²=R⁴=methyl; R³=H;x=2; and z=0) to Form a Strontium Oxide Layer

A strontium oxide layer was deposited on bare silicon by ALD usingalternate pulses of the above-described strontium-containing compound(127° C. bubbler temperature; 154° C. bubbler line temperature) andozone (O₃: 100 standard cubic centimeters per minute (sccm) at 11% inoxygen) at a substrate temperature of 205° C. and a pressure of 10⁻⁴Torr (1.3×10⁻² Pa). Each cycle included a 2 second strontium precursordose, a 30 second pump down, a 1 second ozone dose, and a 60 second pumpdown. The film was deposited using 218 cycles, resulting in anapproximately 250 Å thick strontium oxide layer.

Example 2 Atomic Layer Deposition of a Metal-Containing Compound ofFormula I (M=Sr (n=2); R¹=R⁵=tert-butyl; R²=R⁴=methyl; R³=H; x=2; andz=0) to Form a Strontium Titanate Layer

A strontium titanate layer was deposited on a physical vapor deposited(PVD or sputtered) Pt substrate by ALD using alternate pulses of water(ambient bubbler temperature; 50° C. bubbler line temperature), tetrakistitanium isopropoxide (60° C. bubbler temperature; 112° C. bubbler linetemperature), ozone (O₃: 100 sccm at 11% in oxygen), and theabove-described strontium-containing compound (bubbler temperature of127° C.; bubbler line temperature of 137° C.) at a substrate temperatureof 200° C. and a pressure of 10⁻⁴ Torr (1.3×10⁻² Pa). Each titaniumsequence included a 0.5 second water dose, a 15 second pump down, a 1second titanium precursor dose, and a 15 second pump down. Eachstrontium sequence included a 5 second ozone dose, a 30 second pumpdown, a 2 second strontium precursor dose, and a 30 second pump down.Each cycle included 2 titanium sequences and 1 strontium sequence. Thefilm was deposited using 250 cycles, resulting in an approximately 250 Åthick strontium titanate layer.

Example 3 Atomic Layer Deposition of a Metal-Containing Compound ofFormula I (M=Sr (n=2); R¹=R⁵=isopropyl; R²=R⁴=methyl; R³=H; x=2; andz=0) to Form a Strontium Titanate Layer

A strontium titanate layer was deposited on a PVD Pt substrate by ALDusing alternate pulses of ozone (O₃: 450 sccm at 11% in oxygen),tetrakis titanium isopropoxide (60° C. bubbler temperature; 110° C.bubbler line temperature), ozone (O₃: 450 sccm at 11% in oxygen), andthe above-described strontium-containing compound (bubbler temperatureof 105° C.; bubbler line temperature of 123° C.) at a substratetemperature of 208° C. and a pressure of 10⁻⁴ Torr (1.3×10⁻² Pa). Eachtitanium sequence included a 5 second ozone dose, a 30 second pump down,a 1 second titanium precursor dose, and a 15 second pump down. Eachstrontium sequence included a 5 second ozone dose, a 30 second pumpdown, a 2 second strontium precursor dose, and a 30 second pump down.Each cycle included 1 titanium sequence and 2 strontium sequences. Thefilm was deposited using 100 cycles, resulting in an approximately 50 Åthick strontium titanate layer that was analyzed to containapproximately 29% Sr and 12% Ti.

Example 4 Atomic Layer Deposition of a Metal-Containing Compound ofFormula I (M=Sr (n=2); R¹=R⁵=isopropyl; R²=R⁴=methyl; R³=H; x=2; andz=0) to Form a Strontium Titanate Layer

A strontium titanate layer was deposited on a PVD Pt substrate by ALDusing alternate pulses of ozone (O₃: 450 sccm at 11% in oxygen),tetrakis titanium isopropoxide (60° C. bubbler temperature; 110° C.bubbler line temperature), ozone (O₃: 450 sccm at 11% in oxygen), andthe above-described strontium-containing compound (bubbler temperatureof 105° C.; bubbler line temperature of 137° C.) at a substratetemperature of 212-215° C. and a pressure of 10⁻⁴ Torr (1.3×10⁻² Pa).Each titanium sequence included a 5 second ozone dose, a 30 second pumpdown, a 1 second titanium precursor dose, and a 15 second pump down.Each strontium sequence included a 5 second ozone dose, a 30 second pumpdown, a 2 second strontium precursor dose, and a 30 second pump down.Each cycle included 2 titanium sequences and 1 strontium sequence. Thefilm was deposited using 250 cycles, resulting in an approximately 100 Åthick strontium titanate layer that was analyzed to containapproximately 19% Sr and 21% Ti.

Example 5 Atomic Layer Deposition of a Metal-Containing Compound ofFormula I (M=Sr (n=2); R¹=R⁵=tert-butyl; R²==methyl: R³=H; x=2; and z=0)to Form a Strontium Titanate Lover

A strontium titanate layer was deposited on a PVD Pt substrate by ALDusing alternate pulses of ozone (O₃: 450 sccm at 11% in oxygen),tetrakis titanium isopropoxide (60° C. bubbler temperature; 90° C.bubbler line temperature), ozone (O₃: 450 sccm at 11% in oxygen), andthe above-described strontium-containing compound (bubbler temperatureof 136° C.; bubbler line temperature of 153° C.) at a substratetemperature of 200° C. and a pressure of 10⁻⁴ Torr (1.3×10⁻² Pa). Eachtitanium sequence included a 5 second ozone dose, a 30 second pump down,a 1 second titanium precursor dose, and a 15 second pump down. Eachstrontium sequence included a 5 second ozone dose, a 30 second pumpdown, a 2 second strontium precursor dose, and a 30 second pump down.Each cycle included 2 titanium sequences and 1 strontium sequence. Thefilm was deposited using 250 cycles, resulting in an approximately 200 Åthick strontium titanate layer that was analyzed to containapproximately 21% Sr and 19% Ti.

Example 6 Atomic Layer Deposition of a Metal-Containing Compound ofFormula I (M=Sr (n=2); R¹=R⁵=tert-butyl; R²=R⁴=methyl; R³=H; x=2; andz=0) to Form a Strontium Titanate Layer

A strontium titanate layer was deposited on a PVD Pt substrate by ALDusing alternate pulses of ozone (O₃: 450 sccm at 11% in oxygen),tetrakis titanium isopropoxide (60° C. bubbler temperature; 95° C.bubbler line temperature), ozone (O₃: 450 sccm at 11% in oxygen), andthe above-described strontium-containing compound (bubbler temperatureof 136° C.; bubbler line temperature of 151° C.) at a substratetemperature of 220° C. and a pressure of 10⁻¹ Torr (1.3×10⁻² Pa). Eachtitanium sequence included a 5 second ozone dose, a 30 second pump down,a 1 second titanium precursor dose, and a 15 second pump down. Eachstrontium sequence included a 5 second ozone dose, a 30 second pumpdown, a 2 second strontium precursor dose, and a 30 second pump down.Each cycle included 1 titanium sequence and 1 strontium sequence. Thefilm was deposited using 300 cycles, resulting in an approximately 200 Åthick strontium titanate layer that was analyzed to containapproximately 29% Sr and 12% Ti.

The complete disclosures of the patents, patent documents, andpublications cited herein are incorporated by reference in theirentirety as if each were individually incorporated. Variousmodifications and alterations to this invention will become apparent tothose skilled in the art without departing from the scope and spirit ofthis invention. It should be understood that this invention is notintended to be unduly limited by the illustrative embodiments andexamples set forth herein and that such examples and embodiments arepresented by way of example only with the scope of the inventionintended to be limited only by the claims set forth herein as follows.

1. An atomic layer vapor deposition system comprising: a depositionchamber having a substrate positioned therein; and at least one vesselcomprising at least one compound of the formula (Formula I):

wherein: M is selected from the group consisting of a Group 2 metal, aGroup 3 metal, a Lanthanide, and combinations thereof; each L isindependently an anionic ligand; each Y is independently a neutralligand; n represents the valence state of the metal; z is from 0 to 10;x is from 1 to n; and each R¹, R², R³, R⁴, and R⁵ is independentlyhydrogen or an organic group.
 2. The system of claim 1 wherein each R¹,R², R³, R⁴, and R⁵ is independently hydrogen or an organic group having1 to 10 carbon atoms.
 3. The system of claim 1 further comprising atleast one source of at least one reaction gas.
 4. The system of claim 3wherein the at least one reaction gas is selected from the groupconsisting of oxygen, water vapor, ozone, alcohols, nitrogen oxides,sulfur oxides, hydrogen, hydrogen sulfide, hydrogen selenide, hydrogentelluride, hydrogen peroxide, ammonia, organic amine, silane, disilane,higher silanes, diborane, plasma, air, and combinations thereof.
 5. Thesystem of claim 4 wherein the at least one reaction gas is selected fromthe group consisting of ozone and oxygen.
 6. The system of claim 1further comprising at least one source of an inert gas.
 7. The system ofclaim 6 wherein the inert gas is selected from the group consisting ofnitrogen, helium, argon, and mixtures thereof.
 8. The system of claim 1wherein at least one L is independently selected from the groupconsisting of a halide, an alkoxide group, an amide group, a mercaptidegroup, cyanide, an alkyl group, an amidinate group, a guanidinate group,an isoureate group, a β-diketonate group, a β-iminoketonate group, aβ-diketiminate group, and combinations thereof.
 9. The system of claim 8wherein the at least one L is a β-diketiminate group having a structurethat is the same as that of the β-diketiminate ligand shown in FormulaI.
 10. The system of claim 8 wherein the at least one L is aβ-diketiminate group having a structure that is different than that ofthe β-diketiminate ligand shown in Formula I.
 11. The system of claim 1wherein at least one Y is selected from the group consisting of acarbonyl, a nitrosyl, ammonia, an amine, nitrogen, a phosphine, analcohol, water, tetrahydrofuran, and combinations thereof.
 12. An atomiclayer vapor deposition system comprising: a deposition chamber having asubstrate positioned therein; and at least one vessel comprising atleast one compound of the formula (Formula I):

wherein: M is selected from the group consisting of a Group 2 metal, aGroup 3 metal, a Lanthanide, and combinations thereof; each L isindependently an anionic ligand; each Y is independently a neutralligand; n represents the valence state of the metal; z is from 0 to 10;x is from 1 to n; each R¹, R², R³, R⁴, and R⁵ is independently hydrogenor an organic group; and R¹=R⁵, and R²=R⁴.
 13. The system of claim 12wherein R¹=R⁵=isopropyl.
 14. The system of claim 12 whereinR¹=R⁵=tert-butyl.
 15. The system of claim 12 wherein R²=R⁴=methyl, andR³=H.
 16. The system of claim 15 wherein R¹=R⁵=isopropyl.
 17. The systemof claim 15 wherein R¹=R⁵=tert-butyl.
 18. An atomic layer vapordeposition system comprising: a deposition chamber having a substratepositioned therein; and at least one vessel comprising at least onecompound of the formula (Formula I):

wherein: M is selected from the group consisting of a Group 2 metal, aGroup 3 metal, a Lanthanide, and combinations thereof; each L isindependently an anionic ligand; each Y is independently a neutralligand; n represents the valence state of the metal; z is from 0 to 10;x is from 1 to n; each R¹, R², R³, R⁴, and R⁵ is independently hydrogenor an organic group; and R¹ is different than R⁵.
 19. The system ofclaim 18 wherein R¹=isopropyl, and R⁵=tert-butyl.
 20. The system ofclaim 18 wherein R²=R⁴=methyl, and R³=H.
 21. The system of claim 20wherein R¹=isopropyl, and R⁵=tert-butyl.
 22. An atomic layer vapordeposition system comprising: a deposition chamber having a substratepositioned therein; and at least one vessel comprising at least onecompound of the formula (Formula I):

wherein: M is selected from the group consisting of a Group 2 metal, aGroup 3 metal, a Lanthanide, and combinations thereof; each L isindependently an anionic ligand; each Y is independently a neutralligand; n represents the valence state of the metal; z is from 0 to 10;x is from 1 to n; each R¹, R², R³, R⁴, and R⁵ is independently hydrogenor an organic group; and R² is different than R⁴.
 23. An atomic layervapor deposition system comprising: a deposition chamber having asubstrate positioned therein; and at least one vessel comprising atleast one compound of the formula (Formula I):

wherein: M is selected from the group consisting of a Group 2 metal, aGroup 3 metal, a Lanthanide, and combinations thereof; each L isindependently an anionic ligand; each Y is independently a neutralligand; n represents the valence state of the metal; z is from 0 to 10;x is from 1 to n; each R¹, R², R³, R⁴, and R⁵ is independently hydrogenor an organic group; and at least one vessel comprising at least onemetal-containing compound different than Formula I.
 24. The system ofclaim 23 wherein the metal of the at least one metal-containing compounddifferent than Formula I is selected from the group consisting of Ti,Ta, Bi, Hf, Zr, Pb, Nb, Mg, Al, and combinations thereof.
 25. The systemof claim 23 further comprising at least one source of at least onereaction gas.